localStorage和布尔“字符串" [英] localStorage and boolean 'string'

问题描述

将布尔值存储在localStorage中，此值将转换为字符串. 现在尝试将该值从localStorage转换回布尔值，我需要使用JSON.parse()方法，更方便的!!不起作用.

Storing boolean value in localStorage, this value is converted to string. Now trying to converting back this value from localStorage to boolean, i need to use JSON.parse() method, the more handy !! doesn't work.

代码示例:

var test = false;
localStorage['test'] = test;
console.log("JSON.parse returns: ", JSON.parse(localStorage['test']), "expected: ", test);
console.log("'!!' returns: ", !! localStorage['test'], "expected: ", test);

-jsFiddle-

我很困惑为什么这种行为.有什么解释吗?

I'm quite confused why this behaviour. Any explaination?

PS:在这里使用getter/setter localStorage方法并不重要，结果相同.

PS: using getter/setter localStorage methods doesn't matter here, same result.

推荐答案

无论输入如何，本地存储都会存储字符串(如果您将其与对象一起输入，它将自动以其标准toString()进行转换)方法)...因此，您正在对字符串进行!! test，该字符串始终为true.

Local storage stores strings , I'm afraid, whatever the input (if you feed it with an object, it will be converted automatically with its standard toString() method)... So you're doing !! test on a string, which is always true.

处理存储在JSON.stringify()和JSON.parse() "noreferrer"> DOM存储

You should always use JSON.stringify() and JSON.parse() when dealing with what you store in DOM storage

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